In HWCVD processes, one or more precursor gases are thermally decomposed at a high temperature within a process chamber proximate a substrate upon which a desired material is to be deposited. The thermal decomposition reaction is facilitated within the process chamber by one or more wires, or filaments, supported in the process chamber that may be heated to a desired temperature, for example, by passing electrical current through the filaments.
Use of different filament materials may have an impact on the quality of deposited films. For example, using tantalum filaments in HWCVD applications may result in better quality deposited films, as compared to using tungsten filaments. Unfortunately, however, the inventors have observed that tantalum filaments can be more susceptible to oxidation under certain operating regimes. This undesirably may lead to reduction in current flow through the filament, reduction in the filament temperature, and ultimately, breakage of the filament. The inventors have further observed that this reduction in performance and breakage of the tantalum filament occurs quickly, and thus, tantalum filaments cannot be used for elongated time periods.
Therefore, the inventors have provided improved methods for depositing films using HWCVD processes.